1. Field of the Invention
This invention is related to a cooling structure for a continuous variation transmission system of an all terrain vehicle and in particular to one which can prevent water, dirt and dust from entering the gearbox and enables ease of assembly and maintenance, and also reduces the difficulty in installing other components.
2. Description of the Prior Art
Referring to FIG. 1, in general, all-terrain vehicles 1 are mainly composed of a chassis II, a steering mechanism 12, front wheels 13, a riding seat 14, rear wheels 15, an engine 16 and the continuous variation transmission system 2. A steering mechanism 12 is installed in front of the chassis 11, with a set of front wheels 13 beneath the steering mechanism 12. There is a riding seat 14 on top of the chassis 11, and below the riding seat 14 is the engine 16. The engine 16 drives the continuous variation transmission system 2 by means of the crankshaft, and a set of rear wheels 15 is attached to the continuous variation transmission system 2.
When the all-terrain vehicle 1 is activated, fresh air is introduced from outside and mixed with fuel to form a fuel/air mixture. The oil vapor is then delivered into the engine 16 to initiate power to advance the piston into high-speed reciprocating motion. An interactive crankshaft drives the pulley mechanism and initiates turning of the rear wheels 15, which will lead in the concurrent turning of the front wheels 13 and achieve the purpose of movement.
Referring to FIG. 2, the continuous variation transmission system 2 in the all-terrain vehicle 1 consists of a pulley mechanism 21 placed inside a gearbox 22. The pulley mechanism 21 is composed of a sliding disc 211 placed above a crankshaft 161, a driving plate 212 placed above the crankshaft 161 and to one side of the sliding disc 211, a bracket 213 placed above the crankshaft 161, and to the other side of the sliding disc 211, a counter weight 214 placed amid the sliding disc 211 and the bracket 213 due to the limitation of space, a follower shaft 215 which transmits the power to the rear wheels, a follower disc 216 placed on top of the follower shaft 215, a clutch 217 fixed on top of the follower shaft 215, and a transmission belt 218. The sliding disc 211 and the driving plate 212 constitutes an initiating member of the pulley mechanism 21. One end of said transmission belt 218 is placed in between the driving disc 212 and said sliding disc 211, and the other end is placed amid the follower disc 216. The gearbox 22 has an air inlet 221 and an air exhaust 222 with an inlet conduit 223 attached to the air inlet 221 and an exhaust conduit 224 attached to the air exhaust 222.
Inside the combustion chamber of the vehicle engine 16, the power initiated from combustion explosion will advance the piston into a high-speed reciprocating motion, and consequently initiate the spinning of the crankshaft 161. The sliding disc 211 and the driving disc 212 will spin concurrently and in consequence speed up the spinning of the follower disc 216. Via the clutch 217, the follower shaft 215 will be driven to speed up the spinning and increase the advancing speed of the vehicle. By this time, the high heat produced from spinning of pulley mechanism 21 has to be cooled down by introducing outside cool air from the air inlet conduit 223, and passing through the air inlet 221 to enter the gearbox 22. The hot air will then pass through the exhaust conduit 224 from the air exhaust 222 and exhaust to the outside, to prevent the pulley mechanism 21 from being damaged by overheating.
All terrain vehicles are designed for off-road use, which can support many off-road tasks within seaside, s popular for recreational use such as for use in traveling at seaside, mountains or wild lands. However, the manufacturer must concern about how to prevent sand, dirt and water from entering the gearbox 22 through the air inlet 223 or the air exhaust 224 to cause damage to the belt variation transmission 21. The conventional all terrain vehicle 1 uses an air inlet box 2231 on the air inlet 223 and an air exhaust box 2241 on the air exhaust 224 to obviate the drawbacks. As shown in FIG. 3, the air inlet box 2231 and the air exhaust box 2241 are fastened at an appropriate height under the cover so as to prevent sand, dirt and water from entering the gearbox 22.
Nevertheless, although the conventional cooling device of the terrain vehicle can prevent sand, dirt and water from entering the gearbox 22, it is complicated in structure and difficult to assemble and maintain and needs improvement.